Spring Edge Conditions: Round Edge vs. Deburred Edge

When considering a spring design, it’s important to look at the edge condition of the steel. There’s a vast amount of technical information concerning the edges of the slit strip, but in this blog, we’ll be focusing on the basic characteristics of each edge condition and its benefits.

Springs are typically produced with two edge condition options; deburred spring edges (#5) and round spring edges (#1). Let’s take a closer look at the characteristics of both round spring edges and deburred spring edges to gain a better understanding of the benefits of each.

Round Spring Edges and Deburred Spring Edges – A Brief Guide

#5 Deburred Edge – Deburred edges are considered the default spring edge design for some applications. Deburred spring edges are widely utilized for various types of springs such as conforce and variable force springs. This condition offers square and burr-free spring edges. Below is a magnified photo of this edge:

Below is a graphical representation of the # 5 edge:

To achieve a #1 round edge, the steel strip must undergo additional processing. The square edges are removed, and a smooth, round edge is applied. Then, the strip can be used to manufacture springs. Here are similar photos and graphics of the rounded edge:

Descriptions, photos, and graphics are great, but what’s the point of being so specific about spring edges? Well, both edges have their benefits and costs. The #5 deburred spring edge is a practical option for standard applications. Any burrs from the slitting process have been removed, and the material has undergone the least amount of processing necessary to be ready to be made into a spring. The benefit of this edge is mainly lower cost. Since it requires less processing during manufacturing, it’s more inexpensive than the #1 edge. A spring with a #5 edge will operate reliably in many applications where spring edges aren’t an issue, although it can feel sharp to the touch.

Specifying springs with a #1 edge increases the part cost slightly since the spring material requires more processing than a #5 edge. However, there are a few functional advantages that make the #1 spring edge a necessity in certain situations. For instance, when making a power spring, the round edge is preferred because it maximizes the cycle life of the design. Additionally, the round edge doesn’t damage plastic housings used with power springs or the spool flanges in constant force extension spring designs during regular use.

A spring with deburred edges can cut grooves into a plastic housing or even cause the housing to fail by sawing through it. In either instance, when the spring’s unprocessed edges rub against plastic, flakes of plastic material are created which may degrade spring function and life. The round spring edge may also be preferred in constant force extension spring and constant torque spring designs as a safety consideration if the edges are exposed or handled in any way. The protection of other sensitive components in your designs may also dictate the need for a spring with rounded edges.

Use the information found here as a guideline when considering the edge condition needed for your spring design. At Vulcan Spring, we work with you to develop and finalize unique spring designs that are customized to meet your needs. Once we’ve settled on a design, we’ll provide you with a competitive quote and exceptional spring manufacturing solutions.